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Edexcel C3,C4 June 2013 Thread

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Reply 2900

Zzzyax

Helpful way of understanding transformations.

This is going to sound very, very queer, but just bear with me.

Now,

does not do as it's told. We often substitute the letter 'x' for 'bad' things, so just remember,

is bad. On the other hand,

is good, and does as it's told.

So, if you were to ask x to multiply by 3, as in

, it would do the opposite, because it sucks, and it would divide by 3 instead. If you asked it to move to the left by 2, as in

, it would do the opposite and move right.

So we know that

does as it's told. If we tell it to multiply by 2 and add 3, it'll do it, as in

.

However, the only time that

does as it is told is when you tell it to be naughty. When you put a minus sign in front of it, it just can't resist, and it'll do it, because you're telling it to be bad. So, put a minus sign there, like

, and all the x coordinates become negative. Tell

to become bad, and it'll do it too.

means all of the y coordinates become negative.

Another thing: do things that are closest to the

first.

For example, if you had to sketch

, do the 2 first, then the 5, then the 3.

Reply 2901

Baraf

there was a function question in jan 13 that made no sense, can someone post the jan 13 so I can try it.

Reply 2902

kuku2013

so how's everyone feeling?

Reply 2903

MLogan

Original post by Nitrogen

do you mean jan 13 instead

OH YEAH JAN 13 :| Sorry! Can you help me!

Reply 2904

Kreayshawn

is it correct that we always write the range as:
z < f(x) < y
(with f(x) in the middle and z and y being whatever the lowest and highest is)

how do we lay out the domain?
z < x < y
?

or do we just write co ordinates?

Reply 2905

F1's Finest

I'll be contributing towards helping my fellows brahs and sisters with dropping the grade boundaries.

Reply 2906

Nitrogen

Original post by MLogan

OH YEAH JAN 13 :| Sorry! Can you help me!

Of course. Well if you read the the question carefully it said it wants the maximum value for P(theta). Now look at the fraction, to obtain the maximum value for P(theta) the denominator must be the smallest value possible, hence you want the minimum for Cos(theta).

Reply 2907

Nitrogen

Original post by James A

I'll be contributing towards helping my fellows brahs and sisters with dropping the grade boundaries.

Your help is appreciated :tongue:

Reply 2908

Nilsdejongh

What does everyone think about tomorrow's paper? Any themes that havnt popped up or are going to occur?

The paper style recently is so different to the 05-09/10 ones.. Found jan 13 pretty hard

Reply 2909

_sparks

Can someone please answer these:

Paper E q7

Also is there a method to work out the range/domain of an inverse function from like the domain/range of the normal function.
NOT when they ask the range of one, when they give the domain of the other, because thats simply the same.
But I want to know of a way where we can find out say, the domain function, when we know the domain of the normal function. OR where we have to find the range of the inverse, when we know the range of the normal function.

Someone please help. I really need help :/

Reply 2910

MLogan

Original post by Nitrogen

"the denominator must be the smallest value possible, hence you want the minimum for Cos(theta)" <<This is what i don get ...

Reply 2911

nm786

Original post by bilala2

what are soloman papers. can sum1 link me them please

Solomon Papers: http://papers.xtremepapers.com/Edexcel/Advanced%20Level/Mathematics/Subject%20Sorted/C3/Solomon/
Elmwood papers: http://www.london-oratory.org/maths/

(edited 10 years ago)

Reply 2912

zbert

do we get given the 4 Rsin(x+a) identities if they ask a question where we need to use them?!

Reply 2913

BearOfStown

There will probably be a beasty trig questions with an identity. Im hoping for iterative formula to be late. Could be some sort of functions question with modulus as one hasn't been asked for a while.

Reply 2914

Kreayshawn

in [(x + 2)^2]^3 -- do we multiply the powers or add them? i believe it is multiply but this always confuses me. how do you remember when to add and when to multiply?

(edited 10 years ago)

Reply 2915

Aliyaa

I'm pretty sure I'm just overcomplicating this question and it's easier than it looks, but can someone help me? It's question 2b on the June 2007 C3 paper. How would I find f'(x) of 4x-6/ 2x-1 ?

(edited 10 years ago)

Reply 2916

Westeros

Original post by bestfriends33

Thank you sososo much! You really explained it well!
Just wondering, you know in some trig questions when you have for example sin(2x+35.2) = 0.5 and you need to find x, is it okay to let a letter e.g. b=2x+35.2? Then continue working it out (sinb=0.5, b=30) etc etc. I get the right answers its just that the mark schemes normally don't do this but I find it easier :tongue:

Good luck for tomorrow btw :smile:

hmmm! I guess you could do it that way? just make sure at the end you label your answers x=__, or make sure you write 'Let b =' if that's the way you find it easiest :smile:

Reply 2917

fishnets

Original post by MLogan

"the denominator must be the smallest value possible, hence you want the minimum for Cos(theta)" <<This is what i don get ...

The minimum value for cos theta is -1, if u look at the cos curve find the smallest, positive minimum value, which happens to be pi. So its just: 4/12-10, which gives you 2.

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Reply 2918

nm786

Original post by Aliyaa

I'm pretty sure I'm just overcomplicating this question and it's easier than it looks, but can someone help me? It's question 2b on the June 2007 C3 paper. How would I find f'(x) of 4x-6/ 2x-1 ?

it's in the form

\displaystyle \frac{u}{v}

so use quotient rule.

(edited 10 years ago)

Reply 2919

Mystogan.

Original post by Aliyaa

I'm pretty sure I'm just overcomplicating this question and it's easier than it looks, but can someone help me? It's question 2b on the June 2007 C3 paper. How would I find f'(x) of 4x-6/ 2x-1 ?

Use the quotient rule with u = 4x - 6 and v = 2x - 1

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Edexcel C3,C4 June 2013 Thread

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